[U-Boot] [PATCH v2] dm: remove pre reloc properties in SPL and TPL device tree

Mon Apr 8 15:17:55 UTC 2019

We can remove the pre reloc property in SPL and TPL device-tree:
- u-boot,dm-pre-reloc
- u-boot,dm-spl
- u-boot,dm-tpl
As only the needed node are kept by fdtgrep (1st pass).

The associated function (XXX_pre_reloc) are simple for SPL/TPL:
return always true.


Signed-off-by: Patrick Delaunay <patrick.delaunay at st.com>
---

remove pre reloc properties in SPL and TPL device tree

Patch created after some remarks on previous
http://patchwork.ozlabs.org/patch/1035797/

I check the current code and I found a way to reduce the SPL device tree
size: remove the un-necessary pre reloc parameters in SPL/TPL DT
(as the node check is already managed by fdtgrep)

But I need to change the DM code to avoid the check on presence
of this parameters...

On my board stm32mp1-ev1, the SPL device tree is reduced by 790 bytes
(11149 to 10419) and the SPL binary u-boot-spl.stm32 by 798 bytes
(64745 to 63947); the boot is not broken and I have the expected
delta between generated device tree.

But I am not sure that I see all the side impact of the code change
in SPL/TPL.

PS: I already see a side effect on this patch, because all node are now
    bounded in SPL/TPL, it is no more needed to TAG all the device tree
    path but only the last needed children.
    But in this case phandle for parent node are not keep.


Changes in v2:
- update documentation to describe how the pre-relocation properties
  are used.

 doc/README.SPL              | 16 ++++++++++++++++
 doc/README.TPL              |  4 ++++
 doc/driver-model/README.txt |  4 ++++
 drivers/core/ofnode.c       | 16 ++++++++--------
 drivers/core/util.c         | 31 +++++++++++++++----------------
 scripts/Makefile.lib        |  1 +
 6 files changed, 48 insertions(+), 24 deletions(-)

diff --git a/doc/README.SPL b/doc/README.SPL
index 7a30fef..6eed83f 100644
--- a/doc/README.SPL
+++ b/doc/README.SPL
@@ -66,6 +66,22 @@ CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o)
 CONFIG_SPL_RAM_DEVICE (common/spl/spl.c)
 CONFIG_SPL_WATCHDOG_SUPPORT (drivers/watchdog/libwatchdog.o)
 
+Device tree
+-----------
+The U-Boot device tree is filtered by the fdtgrep tools during the build
+process to generate a much smaller device tree used in SPL (spl/u-boot-spl.dtb)
+with:
+- the mandatory nodes (/alias, /chosen, /config)
+- the nodes with one pre-relocation property:
+  'u-boot,dm-pre-reloc' or 'u-boot,dm-spl'
+
+ftgrep is also used to remove:
+- the properties defined in CONFIG_OF_SPL_REMOVE_PROPS
+- all the pre-relocation properties
+  ('u-boot,dm-pre-reloc', 'u-boot,dm-spl' and 'u-boot,dm-tpl')
+
+All the nodes remaining in the SPL devicetree are bound
+(see driver-model/README.txt).
 
 Debugging
 ---------
diff --git a/doc/README.TPL b/doc/README.TPL
index 980debe..c94129f 100644
--- a/doc/README.TPL
+++ b/doc/README.TPL
@@ -34,6 +34,10 @@ determine which SPL options to choose based on whether CONFIG_TPL_BUILD
 is set. Source files can be compiled for TPL with options choosed in the
 board config file.
 
+TPL use a small device tree (u-boot-tpl.dtb), containing only the nodes with
+the pre-relocation properties: 'u-boot,dm-pre-reloc' and 'u-boot,dm-tpl'
+(see README.SPL for details).
+
 For example:
 
 spl/Makefile:
diff --git a/doc/driver-model/README.txt b/doc/driver-model/README.txt
index 07b120d..532a771 100644
--- a/doc/driver-model/README.txt
+++ b/doc/driver-model/README.txt
@@ -849,6 +849,10 @@ in the device tree node. For U-Boot proper you can use 'u-boot,dm-pre-proper'
 which means that it will be processed (and a driver bound) in U-Boot proper
 prior to relocation, but will not be available in SPL or TPL.
 
+To reduce the size of SPL and TPL, only the nodes with pre-relocation properties
+('u-boot,dm-pre-reloc', 'u-boot,dm-spl' or 'u-boot,dm-tpl') are keept in their
+device trees (see README.SPL for details); the remaining nodes are always bound.
+
 Then post relocation we throw that away and re-init driver model again.
 For drivers which require some sort of continuity between pre- and
 post-relocation devices, we can provide access to the pre-relocation
diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index 0e584c1..5a109dd 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -700,18 +700,18 @@ int ofnode_read_simple_size_cells(ofnode node)
 
 bool ofnode_pre_reloc(ofnode node)
 {
+#if defined(CONFIG_SPL_BUILD) || defined(CONFIG_TPL_BUILD)
+	/* for SPL and TPL the remaining nodes after the fdtgrep 1st pass
+	 * had property dm-pre-reloc or u-boot,dm-spl/tpl.
+	 * They are removed in final dtb (fdtgrep 2nd pass)
+	 */
+	return true;
+#else
 	if (ofnode_read_bool(node, "u-boot,dm-pre-reloc"))
 		return true;
 	if (ofnode_read_bool(node, "u-boot,dm-pre-proper"))
 		return true;
 
-#ifdef CONFIG_TPL_BUILD
-	if (ofnode_read_bool(node, "u-boot,dm-tpl"))
-		return true;
-#elif defined(CONFIG_SPL_BUILD)
-	if (ofnode_read_bool(node, "u-boot,dm-spl"))
-		return true;
-#else
 	/*
 	 * In regular builds individual spl and tpl handling both
 	 * count as handled pre-relocation for later second init.
@@ -719,9 +719,9 @@ bool ofnode_pre_reloc(ofnode node)
 	if (ofnode_read_bool(node, "u-boot,dm-spl") ||
 	    ofnode_read_bool(node, "u-boot,dm-tpl"))
 		return true;
-#endif
 
 	return false;
+#endif
 }
 
 int ofnode_read_resource(ofnode node, uint index, struct resource *res)
diff --git a/drivers/core/util.c b/drivers/core/util.c
index 27a6848..451f772 100644
--- a/drivers/core/util.c
+++ b/drivers/core/util.c
@@ -33,16 +33,15 @@ int list_count_items(struct list_head *head)
 
 bool dm_fdt_pre_reloc(const void *blob, int offset)
 {
+#if defined(CONFIG_SPL_BUILD) || defined(CONFIG_TPL_BUILD)
+	/* for SPL and TPL the remaining nodes after the fdtgrep 1st pass
+	 * had property dm-pre-reloc or u-boot,dm-spl/tpl.
+	 * They are removed in final dtb (fdtgrep 2nd pass)
+	 */
+	return true;
+#else
 	if (fdt_getprop(blob, offset, "u-boot,dm-pre-reloc", NULL))
 		return true;
-
-#ifdef CONFIG_TPL_BUILD
-	if (fdt_getprop(blob, offset, "u-boot,dm-tpl", NULL))
-		return true;
-#elif defined(CONFIG_SPL_BUILD)
-	if (fdt_getprop(blob, offset, "u-boot,dm-spl", NULL))
-		return true;
-#else
 	/*
 	 * In regular builds individual spl and tpl handling both
 	 * count as handled pre-relocation for later second init.
@@ -57,16 +56,16 @@ bool dm_fdt_pre_reloc(const void *blob, int offset)
 
 bool dm_ofnode_pre_reloc(ofnode node)
 {
+#if defined(CONFIG_SPL_BUILD) || defined(CONFIG_TPL_BUILD)
+	/* for SPL and TPL the remaining nodes after the fdtgrep 1st pass
+	 * had property dm-pre-reloc or u-boot,dm-spl/tpl.
+	 * They are removed in final dtb (fdtgrep 2nd pass)
+	 */
+	return true;
+#else
 	if (ofnode_read_bool(node, "u-boot,dm-pre-reloc"))
 		return true;
 
-#ifdef CONFIG_TPL_BUILD
-	if (ofnode_read_bool(node, "u-boot,dm-tpl"))
-		return true;
-#elif defined(CONFIG_SPL_BUILD)
-	if (ofnode_read_bool(node, "u-boot,dm-spl"))
-		return true;
-#else
 	/*
 	 * In regular builds individual spl and tpl handling both
 	 * count as handled pre-relocation for later second init.
@@ -74,7 +73,7 @@ bool dm_ofnode_pre_reloc(ofnode node)
 	if (ofnode_read_bool(node, "u-boot,dm-spl") ||
 	    ofnode_read_bool(node, "u-boot,dm-tpl"))
 		return true;
-#endif
 
 	return false;
+#endif
 }
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 70de9bb..de67677 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -525,4 +525,5 @@ quiet_cmd_fdtgrep = FDTGREP $@
       cmd_fdtgrep = $(objtree)/tools/fdtgrep $(fdtgrep_props) -RT $< \
 		-n /chosen -n /config -O dtb | \
 	$(objtree)/tools/fdtgrep -r -O dtb - -o $@ \
+		-P u-boot,dm-pre-reloc -P u-boot,dm-spl -P u-boot,dm-tpl \
 		$(addprefix -P ,$(subst $\",,$(CONFIG_OF_SPL_REMOVE_PROPS)))
-- 
2.7.4

